DESCRIPTION: (Applicant's Description) The fourth International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine will be held at Nemacolin-Woodland Conference Center near Pittsburgh, Pennsylvania on June 25-28, 1997. This meeting is the fourth in a series that has now become an international forum to discuss and review all aspects of three-dimensional medical imaging. The meetings are held once every two years, alternately in Europe and the U.S. Earlier meetings were held in Corsendonk, Belgium (1991), Snowbird, Utah (1993) and Aix-les-Bains, France (1995). The main focus of the meetings in this series is on research topics related to fully three-dimensional tomography, such as cone-beam tomography in single photon emission computed tomography (SPECT) and x-ray computed tomography (CT), and the reconstruction of volume position emission tomography (PET) images from projections acquired with multi-ring PET scanners with septa retracted. Previous meetings have addressed a wide range of fully three-dimensional techniques, and identified areas for further development and research. Research in PET and SPECT in particular has benefited considerably from this biennial review of the status of fully three-dimensional reconstruction which brings together international experts on all aspects of the field. To reflect the increasing interest in 3D image reconstruction, the Nemacolin meeting will be held over four days. As for the first and second meetings, the Proceedings of the Nemacolin meeting will be published as fully peer-reviewed papers in a Special Issue of Physics in Medicine and Biology in March, 1998. The goal of the Nemacolin meeting is to bring together people actively researching problems related to fully three-dimensional tomography and to encourage open discussion and an exchange of ideas on available techniques. A Critical examination of the problems and practical difficulties of 3D will lead, as from previous meetings, to the formulation of solutions and new advances which improve the imaging of health and disease processes, leading to better health care through improved diagnosis at lower cost.